xref: /petsc/src/dm/tutorials/ex5.c (revision 40badf4fbc550ac1f60bd080eaff6de6d55b946d)
1 
2 static char help[] = "Tests DMDAGetElements() and VecView() contour plotting for 2d DMDAs.\n\n";
3 
4 #include <petscdm.h>
5 #include <petscdmda.h>
6 #include <petscdraw.h>
7 
8 int main(int argc,char **argv)
9 {
10   PetscInt         M = 10,N = 8,ne,nc,i;
11   const PetscInt   *e;
12   PetscErrorCode   ierr;
13   PetscBool        flg = PETSC_FALSE;
14   DM               da;
15   PetscViewer      viewer;
16   Vec              local,global;
17   PetscScalar      value;
18   DMBoundaryType   bx    = DM_BOUNDARY_NONE,by = DM_BOUNDARY_NONE;
19   DMDAStencilType  stype = DMDA_STENCIL_BOX;
20   PetscScalar      *lv;
21 
22   ierr = PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
23   CHKERRQ(PetscViewerDrawOpen(PETSC_COMM_WORLD,0,"",300,0,300,300,&viewer));
24 
25   /* Read options */
26   CHKERRQ(PetscOptionsGetInt(NULL,NULL,"-M",&M,NULL));
27   CHKERRQ(PetscOptionsGetInt(NULL,NULL,"-N",&N,NULL));
28   CHKERRQ(PetscOptionsGetBool(NULL,NULL,"-star_stencil",&flg,NULL));
29   if (flg) stype = DMDA_STENCIL_STAR;
30 
31   /* Create distributed array and get vectors */
32   CHKERRQ(DMDACreate2d(PETSC_COMM_WORLD,bx,by,stype,M,N,PETSC_DECIDE,PETSC_DECIDE,1,1,NULL,NULL,&da));
33   CHKERRQ(DMSetFromOptions(da));
34   CHKERRQ(DMSetUp(da));
35   CHKERRQ(DMCreateGlobalVector(da,&global));
36   CHKERRQ(DMCreateLocalVector(da,&local));
37 
38   value = -3.0;
39   CHKERRQ(VecSet(global,value));
40   CHKERRQ(DMGlobalToLocalBegin(da,global,INSERT_VALUES,local));
41   CHKERRQ(DMGlobalToLocalEnd(da,global,INSERT_VALUES,local));
42 
43   CHKERRQ(DMDASetElementType(da,DMDA_ELEMENT_P1));
44   CHKERRQ(DMDAGetElements(da,&ne,&nc,&e));
45   CHKERRQ(VecGetArray(local,&lv));
46   for (i=0; i<ne; i++) {
47     CHKERRQ(PetscSynchronizedPrintf(PETSC_COMM_WORLD,"i %D e[3*i] %D %D %D\n",i,e[3*i],e[3*i+1],e[3*i+2]));
48     lv[e[3*i]] = i;
49   }
50   CHKERRQ(PetscSynchronizedFlush(PETSC_COMM_WORLD,stdout));
51   CHKERRQ(VecRestoreArray(local,&lv));
52   CHKERRQ(DMDARestoreElements(da,&ne,&nc,&e));
53 
54   CHKERRQ(DMLocalToGlobalBegin(da,local,ADD_VALUES,global));
55   CHKERRQ(DMLocalToGlobalEnd(da,local,ADD_VALUES,global));
56 
57   CHKERRQ(DMView(da,viewer));
58   CHKERRQ(VecView(global,viewer));
59 
60   /* Free memory */
61   CHKERRQ(PetscViewerDestroy(&viewer));
62   CHKERRQ(VecDestroy(&local));
63   CHKERRQ(VecDestroy(&global));
64   CHKERRQ(DMDestroy(&da));
65   ierr = PetscFinalize();
66   return ierr;
67 }
68 
69 /*TEST
70 
71    test:
72      requires: x
73 
74    test:
75      suffix: 2
76      nsize: 2
77      requires: x
78 
79 TEST*/
80